>> example.com. 86400 NS a.example.net. >> example.com. 86400 NS b.example.net. >> example.com. 86400 NS c.example.net. >> >> a.example.net. 3600 A 1.1.1.1 >> b.example.net. 3600 A 2.2.2.2 >> c.example.net. 3600 A 3.3.3.3 >> >> and >> >> example.com. 86400 NS a.example.net. >> >> a.example.net. 3600 A 1.1.1.1 >> a.example.net. 3600 A 2.2.2.2 >> a.example.net. 3600 A 3.3.3.3 >> >> >> Since all the name servers are in example.net zone, these two configure both >> specify three name servers >> for example.com zone and will be affected if example.net name server failed. >> And the latter configuration >> will generate smaller package. But the first configuration seems more >> common, so what’s the benefit? > > From what I understand, when 1.1.1.1 fails to respond, all of > a.example.net will be considered bad, so 2.2.2.2 and 3.3.3.3 won't be > queried at all, and a resolver will return a SERVFAIL.
AFAIK, Recursive name server has name server cache which store several entries, each of them includes zone name ip address other information including RTT, EDNS version, etc So after the recursive name server get the NS records and related glue, both of the configuration should generate similar name server entities, and only if all of them failed to answer the query, the recursive server will return SERVFAIL to resolver. > > -- > Dave Warren > http://www.hireahit.com/ > http://ca.linkedin.com/in/davejwarren > > > _______________________________________________ > dns-operations mailing list > [email protected] > https://lists.dns-oarc.net/mailman/listinfo/dns-operations > dns-jobs mailing list > https://lists.dns-oarc.net/mailman/listinfo/dns-jobs
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